I think that for those of us without landlines, who occasionally forget where we put down the cellphone, this site is a life-saver! I've miss placed my phone on several occasions and it's a very helpless feeling when you live virtually alone.
http://www.wheresmycellphone.com/ You can go online, and call your cell for free, so you can track down the ringing. Now I don't have to get in the car, drive to my dad's, tell him to give me 10 minutes to get home, then start calling my cellphone till I pick up. Yay!